The quality and safety of medication management can be improved by adopting health information technology. As patients transfer among community-based and hospital providers, there are numerous opportunities for medication errors. The Institute of Medicine reported that inaccurate medication lists in ambulatory clinics caused a larger number of fatal adverse drug effects than in a hospital setting. In fall 2008, NewYork-Presbyterian (NYP) instituted an interdisciplinary, electronic process for reconciling patients'medications as they transitioned from ambulatory-to-hospital and hospital-to-ambulatory care settings. The process improved compliance of documenting attestation of medication reconciliation at hospital admission from less than 40% to over 95%. Before the adoption of the medication reconciliation process, preadmission medications and discharge medications were stored as free-text in the electronic health record (EHR). After the adoption, medications were managed using a structured electronic medication list shared across NYP's ambulatory EHR and inpatient EHR. A formal study of the medication reconciliation process at NYP can serve as a benchmark for future IT implementations addressing medication reconciliation. The NYP process is innovative because 1) it does not require paper forms;2) it uses a commonly-deployed commercial EHR;and 3) it uses a medication list based on discrete, coded elements that bridges ambulatory and inpatient care settings. Methods: In addition to improving documentation compliance, we hypothesize that the implementation of the electronic medication reconciliation process affected provider workflow, medication list completeness, and the rate of potentially-harmful unintentional medication discrepancies. We will evaluate this hypothesis by engaging clinical experts to review electronic charts for patients who transitioned from ambulatory ? inpatient ? ambulatory care settings. We will examine the medication lists at each point of transition, and review information from clinical notes and other electronic data sources. Expected Outcomes: We believe that a shared, structured medication list that spans ambulatory and inpatient care settings is the best way to improve the quality and safety of medication management. However, the benefits of using a shared electronic medication list across ambulatory and inpatient care settings have not been proven scientifically. We are in a unique position to assess the benefits of a shared medication list and whether it improved medication management in our care setting. Most changes to a patient's medication regimen through the care continuum are likely intended and documented by the patient's care provider. Sometimes, unintentional medication discrepancies may exist that have potential to cause patient harm. This study will yield knowledge on whether the adoption of a fully-electronic medication reconciliation process was associated with a decline in rate of potentially-harmful unintentional medication discrepancies across care settings.